Oldest to newest:
(Vintage) Koss / Realistic Pro 20
Price: ? No idea, I think I was in Mddle School! :-)
Condition: The cup pads are stiff, but intact and mostly undformed, the headband is intact but the rubber feels like it could be a little crumbly if you pushed it too hard. Minor scratches on plastic, cord is intact and plyble, repair on the jack.
(Vintage) Sennheiser HD410 SL
Price: ? Don't remember
Condition: Needs new ear pads. Other than that pretty much mint.
Koss / Radio Shack KTXPRO1 / PRO 35 A
Year: Various, I've replaced these multiple times over the years.
Condition: Poor, Daily usage, pads bad insulation broken
Extreme Isolatoin EX 29
Contition: Replaced ear pads, otherwise good.
Monster Beats Studio By Dr. Dre
Condition: Used by me. Ear pads in good condition, top band cusion showing wear, minor knicks and scratches on plactic.
Sennheiser HD 58X Jubilee (Massdrop)